Teenagers are hard-wired to be night owls, explains Stephanie J. Crowley, PhD, an associate professor in Rush's Department of Behavioral Sciences. "The biology that regulates sleep timing changes during puberty," she says.
As a result, teens are programmed to stay up approximately two hours later than they did as children, according to Crowley. At age 9 or 10, children go to sleep between 9 or 10 p.m., on average. By age 17, sack times shift to between 11 p.m. and midnight.
Not surprisingly, these late nights translate into sleep-deprived adolescents, particularly when school schedules require early wake-up times. Sixty-nine percent of high school students get fewer than eight hours of sleep on school nights, according to a study by the Centers for Disease Control and Prevention.
Yet teenagers ages 14 to 17 need at least eight and as many as 10 hours of sleep per night, according to National Sleep Foundation recommendations. (Younger children ages 6 to 13 need 9 to 11 hours.)
To help counteract the teen sleep deprivation epidemic, Crowley and her colleagues in Rush's Biological Rhythms Research Laboratory are exploring the use of bright-light therapy to fine-tune adolescent biological sleep clocks. Previous research at Rush and elsewhere has found that light exposure can help adjust adult sleep patterns. Can it also help teens? Crowley aims to find out.
Taking steps to address teen sleepiness could provide major public health benefits, she says. For one, it could reduce car accidents caused by groggy teens. Plus, it could improve teen health. Sleep deprivation is associated with depression, obesity and poor emotional control in teens, as well as higher rates of alcohol, nicotine and marijuana use.
The biology of teen sleep
Two biological systems help people maintain regular, healthy sleep levels - and both systems undergo changes when adolescents hit puberty.
One is homeostasis, which is the body's ability to regulate internal processes (for example, maintaining a normal temperature). When it comes to sleep, the body constantly balances wake and sleep times. "The more you sleep the more you want to wake up, and the more you are awake the more you want to sleep," Crowley says.
Sleep pressure, or the physical drive to sleep, builds over the course of a day. However, a change takes place at puberty.
"The buildup of sleep pressure accumulates at a slower rate in older adolescents compared to their less mature brothers and sisters," Crowley says. "That helps them stay awake later in the evening to finish homework or post on Instagram."
The second system regulating sleep is the body's central clock, a tiny area of the brain called the suprachiastic nucleus. This clock controls what are known as circadian rhythms. "Our bodies have a lot of rhythms like when we are supposed to be asleep or awake, when we are supposed to eat or fast, and when different hormone levels go up and down," Crowley explains.
Around the time of puberty, the circadian rhythms related to sleep start kicking in later in the evening, contributing to the teenage night owl propensity.
Bright light and sleep patterns
Exposure to light is known to affect the body's circadian rhythms. Research by Crowley's Rush colleagues Charmane Eastman, PhD, professor of behavioral sciences, and Helen Burgess, PhD, director of the Biological Rhythms Research Laboratory, shows that adults can reset their wake-up and sleep times earlier by spending time outside or near bright light soon after waking up.
This treatment can come in handy for adults who need to rise early for work or to adjust to different time zones. The opposite is also true: Bright light exposure in the evening shifts adult sleep/wake-up times later.
To learn if adolescents have a similar response to bright light exposure, Crowley is conducting two studies, both funded by the National Institutes of Health. The first, which will wrap up this summer, is following teen volunteers for one month.
Most of the month, the teens sleep at home according to a set schedule. The teens also spend five nights in Rush's Biological Rhythms Research Laboratory, which is equipped with bedrooms, a kitchen, and reclining chairs where the teens can watch TV or movies. "It's like a first-class airplane ride," Crowley says with a laugh.
During their time at the lab, the teens are exposed to bright light. "We use bright light boxes, which are safe and do not release UV rays," Crowley says. "They're brighter than normal indoor lighting but not as bright as being outside on a sunny day."
The teens provide saliva samples to measure melatonin levels, which directly correspond with circadian sleep rhythms. At the conclusion of the study, Crowley will compare the melatonin levels with the use of the bright light treatment to see how the circadian clock reacts. "We will be able to determine what time of day is best for an adolescent to get bright light and when a teen should avoid bright light that may make their sleep later," she says.
The second study is just getting underway. It is focused on determining the amount of bright light necessary to shift sleep patterns in teenagers. Teens sleep at home for most of the study and spend two weekends in the lab.
Interested teens and their parents can call the Biological Rhythms Research Laboratory at(312) 942-9991 to find out if they qualify for the study.
Crowley also wants to see if light therapy is feasible for teens. "We don't know how long adolescents are willing to sit in front of a light box," she says.
Healthy habits for healthy zzzs
Signs that a teenager is sleep deprived include difficulty rising in the morning, falling asleep at inappropriate times (for example, while watching TV), and sleeping two or more additional hours on Saturdays and Sundays than weekdays.
What can parents do to help their teens get needed sleep? The first thing is to make sleep a priority for the entire family.
"Families need to be prioritizing sleep as a unit," Crowley says. "Mom and Dad should be demonstrating good sleep habits to show their teen that they take sleep very seriously."
One of the most important sleep habits to adopt is a regular bedtime. "Consistency is key for teens." Crowley says. I think there needs to be a negotiation between parents and teenagers about a set bedtime and a time when they will start to wind down at night."
Crowley also recommends these healthy sleep habits:
- Keep electronics and devices out of the bedroom, particularly at night.
- Set a media curfew, or a negotiated time in the evening when all electronics and devices are turned off and/or put on a charger out of site.
- Avoid caffeine late in the day.
- Try to get up around the same time on the weekends as on weekdays-and take an afternoon nap if sleepy.
- Avoid napping more than 30 to 45 minutes.
Crowley cannot yet give specific instructions on how to use bright light therapy to sync teenage sleep patterns with school day schedules. However, teens can try getting outside in morning daylight to see if it helps keep their circadian rhythms timed for early wake ups.
The key is to do it on weekends as well as weekdays. "Don't sleep in too much on weekends, and then get outside as soon as possible," Crowley says. "That will help your circadian system stay in sync with your school day rhythm."
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